Page:Transactions of the Geological Society, 1st series, vol. 2.djvu/231

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221
Mr. Webster on the Strata lying over the Chalk.

M. Brongniart mentions the following as being found in the
various beds of the upper marine marls.

Cytherea (bom-bees) Ostrea Hippopus
– – – – – plana – – – – Pseudochama
– – – – – elegans – – – – longirostris
– – – – – semisulcata – – – – canalis
Cerithium plicatum – – – – cochlearia
– – – – – cinctum – – – – cyathella
Ampullaria patula – – – – spatulata
Cardium obliquum – – – – linguatula
Nucula margaritacea Bones and parts of Fishes
Patella spirorostris—Cuv. p. 187.
In the upper marine sand stones.
Oliva mitreola Pectunculus pulvinatus
Fusus, resembling longævus Crassatella compressa?
Cerithium cristatum Donax retusa?
– – – – – – lamellosum Cytherea nitidula
– – – – – – mutabile? – – – – – lævigata
Solarium? – – – – – elegans?
Melania costellata? Corbula rugosa
Melania? Ostrea flabellula

I have already mentioned that considerable difficulties appear to me to exist in assigning a place to the Woolwich beds. The actual lowness of their level, appearing to dip under the London clay, and their situation near the chalk without the intervention of that bed, at first seem to determine their geognostic position. Whilst the circumstances of their not being seen in any part covered by